Revenue Recognition (Schedule of Consolidated Statement of Cash Flows) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating Activities
Net income	$ 83,019	$ 32,585	$ 52,812
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	68,800	61,517	58,106
Amortization	10,236	10,439	9,355
Change in other noncurrent liabilities	(5,479)	(10,145)	(5,232)
Change in deferred taxes and other liabilities	8,972	(1,264)	5,889
Provision for write-off of property, plant and equipment	3,707	2,870	2,778
Non-cash interest expense	459	660	564
Write-off of pension liability adjustment due to settlement/curtailment	1,494		51
Compensation and benefits paid or payable in Class A Common Stock	2,203	2,133	2,433
Changes in operating assets and liabilities that provided/(used) cash, net of impact of business acquisition:
Accounts receivable	(19,139)	(21,859)	(12,697)
Contract assets	(10,267)
Inventories	(968)	3,090	(12,520)
Prepaid expenses and other current assets	(5,815)	(4,989)	(2,595)
Income taxes prepaid and receivable	(1,402)	(941)	(2,206)
Noncurrent receivables	(12,249)	(18,766)	(14,045)
Accounts payable	9,340	2,910	2,108
Accrued liabilities	8,209	5,303	1,312
Income taxes payable	(824)	(799)	1,398
Other, net	(7,811)	(2,677)	(6,571)
Net cash provided by operating activities	132,485	64,216	80,940
Net cash used in investing activities	(82,886)	(87,637)	(253,553)
Net cash (used in)/provided by financing activities	(27,258)	12,867	172,038
Effect of exchange rate changes on cash and cash equivalents	(8,313)	12,539	(2,796)
Increase/(decrease) in cash and cash equivalents	14,028	1,985	(3,371)
Cash and cash equivalents at beginning of year	183,727	181,742	185,113
Cash and cash equivalents at end of year	197,755	183,727	$ 181,742
As reported [Member]
Operating Activities
Net income	83,019
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	68,800
Amortization	10,236
Change in other noncurrent liabilities	(5,479)
Change in deferred taxes and other liabilities	8,972
Provision for write-off of property, plant and equipment	3,707
Non-cash interest expense	459
Write-off of pension liability adjustment due to settlement/curtailment	1,494
Compensation and benefits paid or payable in Class A Common Stock	2,203
Changes in operating assets and liabilities that provided/(used) cash, net of impact of business acquisition:
Accounts receivable	(19,139)
Contract assets	(10,267)
Inventories	(968)
Prepaid expenses and other current assets	(5,815)
Income taxes prepaid and receivable	(1,402)
Noncurrent receivables	(12,249)
Accounts payable	9,340
Accrued liabilities	8,209
Income taxes payable	(824)
Other, net	(7,811)
Net cash provided by operating activities	132,485
Net cash used in investing activities	(82,886)
Net cash (used in)/provided by financing activities	(27,258)
Effect of exchange rate changes on cash and cash equivalents	(8,313)
Increase/(decrease) in cash and cash equivalents	14,028
Cash and cash equivalents at beginning of year	183,727
Cash and cash equivalents at end of year	197,755	183,727
Adjustments to reverse effects of ASC 606 [Member]
Operating Activities
Net income	(2,448)
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation
Amortization
Change in other noncurrent liabilities
Change in deferred taxes and other liabilities	(877)
Provision for write-off of property, plant and equipment
Non-cash interest expense
Write-off of pension liability adjustment due to settlement/curtailment
Compensation and benefits paid or payable in Class A Common Stock
Changes in operating assets and liabilities that provided/(used) cash, net of impact of business acquisition:
Accounts receivable	(17,387)
Contract assets	10,267
Inventories	10,433
Prepaid expenses and other current assets
Income taxes prepaid and receivable
Noncurrent receivables
Accounts payable
Accrued liabilities	12
Income taxes payable
Other, net
Net cash provided by operating activities
Net cash used in investing activities
Net cash (used in)/provided by financing activities
Effect of exchange rate changes on cash and cash equivalents
Increase/(decrease) in cash and cash equivalents
Cash and cash equivalents at beginning of year
Cash and cash equivalents at end of year
As adjusted to exclude adoption of ASC 606 [Member]
Operating Activities
Net income	80,571
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	68,800
Amortization	10,236
Change in other noncurrent liabilities	(5,479)
Change in deferred taxes and other liabilities	8,095
Provision for write-off of property, plant and equipment	3,707
Non-cash interest expense	459
Write-off of pension liability adjustment due to settlement/curtailment	1,494
Compensation and benefits paid or payable in Class A Common Stock	2,203
Changes in operating assets and liabilities that provided/(used) cash, net of impact of business acquisition:
Accounts receivable	(36,526)
Contract assets
Inventories	9,465
Prepaid expenses and other current assets	(5,815)
Income taxes prepaid and receivable	(1,402)
Noncurrent receivables	(12,249)
Accounts payable	9,340
Accrued liabilities	8,221
Income taxes payable	(824)
Other, net	(7,811)
Net cash provided by operating activities	132,485
Net cash used in investing activities	(82,886)
Net cash (used in)/provided by financing activities	(27,258)
Effect of exchange rate changes on cash and cash equivalents	(8,313)
Increase/(decrease) in cash and cash equivalents	14,028
Cash and cash equivalents at beginning of year	183,727
Cash and cash equivalents at end of year	$ 197,755	$ 183,727